arduino - AVR linker error, "relocation truncated to fit"

Question

I'm trying to compile some code for an ATmega328 micro, and I want use the libraries and the core of Arduino. I'm using CMake. I have gotten to compile the core library and all objects of my code and the libraries of Arduino. But when it's linking, they show me the following error.

..."relocation truncated to fit: R_AVR_13_PCREL against symbol"..."avr5/libgcc.a"...

I have found through Google that this is a common error, but no solution has worked for me. The only thing I can't do is put "-lm" and "-lc" flags at the end of the linker sentence, because I don't know how I can do it with CMake.

EDIT: I have tried compile it with makefile too but I have gotten the same result, even putting "-lm" and "-lc" flags at the end of the linker sentence.

I put my Makefile and CMake files here:

---

CMakeList.txt The main CMake file

cmake_minimum_required(VERSION 2.6)
Project(IMU)

set(ARDUINO_PROCESSOR atmega328p)
set(ARDUINO_PROCESSOR_FREQ 1600000L)

include(./arduino.cmake)

add_library(ardlib
        libraries/EEPROM/EEPROM.cpp
        libraries/Wire/utility/twi.c
        libraries/Wire/Wire.cpp
        libraries/HMC58X3/HMC58X3
        )

LINK_DIRECTORIES(${IMU_SRC_DIR}/libarduinocore
        ${IMU_SRC_DIR}/libraries/EEPROM
        ${IMU_SRC_DIR}/libraries/Wire
        ${IMU_SRC_DIR}/libraries/HMC58X3
        )

link_libraries(arduinocore ardlib)

include_directories(
        libarduinocore
        libraries/EEPROM
        libraries/Wire
        libraries/Wire/utility
        libraries/HMC58X3
        )

set(C_SRCS
        ADXL345.cpp
        ApplicationRoutines.cpp
        DCM.cpp
        HMC5883L.cpp
        ITG3200.cpp
        matrix.cpp
        output.cpp
        timing.cpp
        vector.cpp
        )

set(C_HDRS
        ADXL345.h
        ApplicationRoutines.h
        DCM.h
        HMC5883L.h
        ITG3200.h
        matrix.h
        output.h
        timing.h
        vector.h
        declarations.h
        )

add_executable(IMU.elf main.cpp ${C_SRCS} ${C_HDRS})

add_subdirectory(libarduinocore)

arduino.cmake. That is imported by CMakeList.txt:

set(ARDUINO_PROCESSOR atmega328p)
set(ARDUINO_PROCESSOR_FREQ 16000000L)

# This module defines macros intended for use by cross-compiling toolchain files when
# CMake is not able to automatically detect the compiler identification.
include (CMakeForceCompiler)

# Set this for cross compiling.  Otherwise it is set to CMAKE_HOST_SYSTEM_NAME,
# which is the system we are developing on.
set (CMAKE_SYSTEM_NAME Generic)

# It sets CMAKE_<lang>_COMPILER to the given compiler and the cmake internal variable
# CMAKE_<lang>_COMPILER_ID to the given compiler-id. It also bypasses the check for
# working compiler and basic compiler information tests.
SET(CMAKE_C_COMPILER avr-gcc)
SET(CMAKE_CXX_COMPILER avr-g++)
cmake_force_cxx_compiler (avr-g++ CrossAVR)
cmake_force_c_compiler (avr-gcc CrossAVR)

# Appparently we want to use the gnuc99 standard.
#set (CSTANDARD "-std=gnu99")

# Generate .stabs debugging symbols for assembler source lines. This enables avr-gdb to
# trace through assembler source files.
#set (CDEBUG "-gstabs")

# Warn for functions declared or defined without specified argument types.
set (CWARN "-Wall -Wstrict-prototypes")

# -funsigned-char - Make any unqualfied char type an unsigned char. Without this option,
#   they default to a signed char.
# -funsigned-bitfields - Make any unqualified bitfield type unsigned. By default,
#    they are signed.
# -fpack-struct - Pack all structure members together without holes.
# -fshort-enums - Allocate to an enum type only as many bytes as it needs for the declared
#   range of possible values. Specifically, the enum type will be equivalent to the
#   smallest integer type which has enough room.
set (CTUNING_FLAGS "-ffunction-sections -fdata-sections -funsigned-char -funsigned-bitfields -fpack-struct -fshort-enums")

# Optimize for size.   The special option -Os is meant to turn on all -O2 optimizations
# that are not expected to increase code size.
set (COPT "-Os")

SET(CINCS "-I${ArduinoCode_SOURCE_DIR}/libarduinocore")

# Finally the compilation flags are now configured.
set(CMAKE_CXX_FLAGS "-lc -lm -mmcu=${ARDUINO_PROCESSOR} -DF_CPU=${ARDUINO_PROCESSOR_FREQ} ${CTUNING_FLAGS} ${CWARN} ${CSTANDARD} ${CDEBUG} ${COPT} ${CINCS} -lc")
set(CMAKE_C_FLAGS "-lc -lm ${CMAKE_CXX_FLAGS} ${CTUNING_FLAGS} ${CWARN} ${CSTANDARD} ${CDEBUG} ${CINCS} -lc")

# On gentoo, -rdynamic is passed to the compiler. The avr compiler does not recognize this
# option.  Also, we are not building shared libraries.
set(CMAKE_EXE_LINKER_FLAGS "-Wl,--gc-sections")
set(CMAKE_SHARED_LIBRARY_LINK_CXX_FLAGS ""

Arduino core CMake file. This is a CMakeList.txt file put into libarduinocore directory.

include(../arduino.cmake)


add_library (arduinocore
        HardwareSerial.cpp
        pins_arduino.c
        Print.cpp
        Tone.cpp
        WInterrupts.c
        wiring_analog.c
        wiring.c
        wiring_digital.c
        wiring_pulse.c
        wiring_shift.c
        WMath.cpp
        WString.cpp
        )

Makefile

TARGET = IMU
PORT = /dev/ttyACM0
BAUD = 57600
PROGRAMMER = arduino
MCU = atmega328p
F_CPU = 8000000L

CXX_SRCS = ADXL345.cpp 
           ApplicationRoutines.cpp 
           DCM.cpp 
           HMC5883L.cpp 
           ITG3200.cpp 
           matrix.cpp 
           output.cpp 
           timing.cpp 
           vector.cpp

CXX_OBJ = $(CXX_SRCS:.cpp=.o)

CXX_HDRS = ADXL345.h 
           ApplicationRoutines.h 
           DCM.h 
           declarations.h 
           HMC5883L.h 
           ITG3200.h 
           matrix.h 
           output.h 
           timing.h 
           vector.h

CORE_DIR = libarduinocore

CORE_CXX_SRCS = $(CORE_DIR)/HardwareSerial.cpp 
                $(CORE_DIR)/Print.cpp 
                $(CORE_DIR)/Tone.cpp 
                $(CORE_DIR)/WMath.cpp 
                $(CORE_DIR)/WString.cpp

CORE_CXX_OBJ = $(CORE_CXX_SRCS:.cpp=.o)                                                                                                                                                                        

CORE_CC_SRCS = $(CORE_DIR)/pins_arduino.c                                                                                                                                                                     
               $(CORE_DIR)/WInterrupts.c                                                                                                                                                                      
               $(CORE_DIR)/wiring_analog.c                                                                                                                                                                    
               $(CORE_DIR)/wiring.c                                                                                                                                                                           
               $(CORE_DIR)/wiring_digital.c                                                                                                                                                                   
               $(CORE_DIR)/wiring_pulse.c                                                                                                                                                                     
               $(CORE_DIR)/wiring_shift.c                                                                                                                                                                      

CORE_CC_OBJ = $(CORE_CC_SRCS:.c=.o)                                                                                                                                                                            

CORE_HDRS = $(CORE_DIR)/binary.h                                                                                                                                                                              
            $(CORE_DIR)/HardwareSerial.h                                                                                                                                                                      
            $(CORE_DIR)/pins_arduino.h                                                                                                                                                                        
            $(CORE_DIR)/Print.h                                                                                                                                                                               
            $(CORE_DIR)/Stream.h                                                                                                                                                                              
            $(CORE_DIR)/WCharacter.h                                                                                                                                                                          
            $(CORE_DIR)/WConstants.h                                                                                                                                                                          
            $(CORE_DIR)/wiring.h                                                                                                                                                                              
            $(CORE_DIR)/wiring_private.h                                                                                                                                                                      
            $(CORE_DIR)/WProgram.h                                                                                                                                                                            
            $(CORE_DIR)/WString.h

ARD_LIB_DIR = libraries

ARD_LIB_CXX_SRCS = $(ARD_LIB_DIR)/EEPROM/EEPROM.cpp 
                   $(ARD_LIB_DIR)/Wire/Wire.cpp 
                   $(ARD_LIB_DIR)/HMC58X3/HMC58X3.cpp
ARD_LIB_CC_SRCS = $(ARD_LIB_DIR)/Wire/utility/twi.c

ARD_LIB_CXX_OBJ = $(ARD_LIB_CXX_SRCS:.cpp=.o)
ARD_LIB_CC_OBJ = $(ARD_LIB_CC_SRCS:.c=.o)

CC = avr-gcc
CXX = avr-g++
OBJCOPY = avr-objcopy
OBJDUMP = avr-objdump
AR  = avr-ar
SIZE = avr-size
NM = avr-nm
AVRDUDE = avrdude

ARD_LIB_INC = -I$(ARD_LIB_DIR) -I$(ARD_LIB_DIR)/EEPROM -I$(ARD_LIB_DIR)/Wire -I$(ARD_LIB_DIR)/HMC58X3 -I$(ARD_LIB_DIR)/Wire/utility

FLAGS_WARN = -Wall -Wstrict-prototypes
FLAGS_TUNING = -ffunction-sections -fdata-sections -funsigned-char -funsigned-bitfields -fpack-struct -fshort-enums
FLAGS_OPT = -Os

ALL_INC = -I. $(ARD_LIB_INC) -I$(CORE_DIR)
OBJS = $(CXX_OBJ) $(CORE_CXX_OBJ) $(COR

Answer 1

Explanation:

As the error message suggests, the issue has to do with the relocation (of code) which causes some truncation to occur. The message comes from the linker which is trying to map pieces of code to appropriate locations in the program memory.

When code is placed or moved to some location ("relocation") and this code is referred to from another piece of code, via JMP or CALL (i.e. a function call), the relocated address has to be added to the JMP or CALL instruction referring to it.

The AVR devices support two kinds of jump/call instructions: JMP vs. RJMP, and CALL vs. RCALL. The R variants make calls relative to the current location and are more efficient both in usage of program memory and execution time. This comes at a cost though: RJMP and RCALL can only be used for addresses in the range of +/-4kb from their location in program memory. This is never a problem on devices with no more than 8kb of program memory because the whole 8kb range can be addressed from any location via RCALL or RJMP.

On devices with more than 8kb of program memory, however, this is not true for all possible locations. Therefore, if the linker decides it can put the code to be called within the +/-4kb range from the RJMP/RCALL there will be no problem, but if the linker fails to (re-)locate the code to be within that range, RJMP/RCALL cannot be used to reach the code's new address, the address is thus truncated (just like when doing uint16_t value = 12345; uint8_t truncatedValue = value; in C) and the generated code breaks.

Note that this may or may not happen for any given project exceeding 4kb of program memory (on devices with >8kb of program memory) at some point, because it depends on the relocation of code needed, which may basically change with every new line of C code added or removed, with every library added to be linked in, or even the order in which the libraries or other pieces of code are linked in (e.g. calling from "A" to "B" may work when the linker locates the code like "A B C" but fail when the linker decides to relocate like "A C B").

Solution:

You have to let the compiler know that it needs to generate JMP/CALL instructions instead of the (more efficient) RJMP/RCALL instructions. In AVR Studio/Atmel Studio this can be done in the project's properties, toolchain, AVR/GNU C compiler, optimization. The relevant option is "Use rjmp/rcall (limited range) on >8k devices (-mshort-calls)" which needs to be unchecked to prevent the named error.
As the label indicates, the relevant command line option is -mshort-calls which needs to be removed from the gcc command line parameter list to achieve the same when invoking gcc from outside of the IDE.

Update:

To avoid the unnecessary confusion this error may cause -mshort-calls was deprecated in avr-gcc 4.7 and will be removed from 4.8. Source: GCC 4.8 Changes.

Users should now use -mrelax instead to generate binaries that have the call optimizations where possible but will never produce the error.